This is definitely a gambling because every one put a stake in order to get the pooled money.
Yes, it is gambling. Whether it is not considered gambling in the traditional sense of the term is another matter, but everything in life evolves.
I wouldn't call it gambling. That's a tournament, a competition.
A tournament or competition where you put in some money at the beginning and can end up winning more. In other words, gambling.
It's still gambling because you're spending money to earn money and competing with other people for the prize money.
That's it.